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F R A U N H O F E R I N S T I T U T E F O R
R E L I A B I L I T Y A N D M I C R O I N T E G R AT I O N I Z M
MICRO BATTERY pROTOTYpING
Micro battery prototyping line at Fraunhofer IZM
Cover: Micro battery fabrication on silicon wafer substrate
In cooperation with
CONTACT
Fraunhofer Institute for
Reliability and Microintegration IZM
Gustav-Meyer-Allee 25
13355 Berlin
Germany
Dr. Robert Hahn
Phone: +49 30 46403-611
www.izm.fraunhofer.de/micro_energy_systems
EXpERTISE AND SOLUTIONS
We propose a range of cooperation models, from direct
contract research performed by Fraunhofer IZM through
joining an EU, federal or national government funded
scientific research project.
SERVICES
• Design and technology development for custom size
lithium ion micro batteries
• Consulting and application advice for micro batteries
• Primary and secondary battery testing services
• Specialized research on battery life-time issues such
as diffusion barriers, encapsulation and material
compatibility. Areas of interest include higher operating
temperatures, pressures, and high-g environments
• Silicon and printed circuit board expertise for battery
integration and packaging
• Electrochemical test cells and material development for
novel battery chemistries
Printed stack of anode (LTO), seperator (SiO2) and cathode (NCA)
The Fraunhofer IZM’s 10 m battery development and assembly line for the high-precision manufacturing of minute custom-design micro batteries
SCOpE
We aim to provide extremely miniaturized wireless power
sources for applications such as implantable and semi-
implantable medical devices, miniaturized data loggers, active
RFID and smart jewellery. In the longer term, we aim to
enable rechargeable batteries for higher temperatures up to
140 °C.
Direct battery integration in silicon saves packaging material
and allows better miniaturization as well as providing a novel
route for in-house small production runs. Current plans
include RF and PV recharging prototypes.
CHALLENGES ADDRESSEDWe build on in-house know-how of wafer-level packaging
microelectronics, microfluidic electrolyte handling and battery
materials processing, including the production of hermetically
sealed casings under argon, to prevent humidity permeation.
SELLING pROpOSITION
• Prototype primary and secondary lithium-ion battery in a
novel silicon package
• 1.5 V, 2.2 V or 3.7 V systems
• Minimum size is 0.5 mm x 0.5 mm x 0.2 mm (LxBxH)
• Cost between 0.4 and 4 €, between 1 and 20 mm2
footprint (24 wafers production run)
• Application-specific form factor possible; any 2.5D shape
• State-of-the-art battery materials including bio-
compatible electrolytes
• Cell capacity: 7 … 30 µAh/mm2 depending on electrode
choice and thickness
• Energy density: 200 mWh/cm3 even with the smallest size
• Low impedance for pulse load; tested for bluetooth low
energy (BLE)
• Dedicated battery management for smallest batteries
• > 750 recharge cycles demonstrated
• Safe for deep discharge
• Temperatures: 80 °C for 24 hours, -20°C … 60 °C
operation range
pROTOTYpE MANUFACTURING
• Wafer level processing including through silicon/glass vias,
handling of thin wafers on carriers and wafer bonding.
• Precision screen-printing and robot dispensing for the
integration of battery electrodes.
• Microfluidic electrolyte injection.
• Substrate bonding for a secure assembly and sealing of
base and top substrates of the battery housing
• Simultaneous fabrication of thousand batteries on a
wafer substrate.
Dispenser-printing of battery materials into silicon battery housing (left) and
cycle stability at 0.5 C (right)
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Smallest micro battery: electrodes on the silicon wafer (left) and hermetically
packaged, singulated batteries 0.5 x 8 mm2 on one cent coin (right)
100 µm